xt_iprange.c

Go to the documentation of this file.

/*
 *  xt_iprange - Netfilter module to match IP address ranges
 *
 *  (C) 2003 Jozsef Kadlecsik <[email protected]>
 *  (C) CC Computer Consultants GmbH, 2008
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_iprange.h>

static bool
iprange_mt4(const struct sk_buff *skb, struct xt_action_param *par)
{
    const struct xt_iprange_mtinfo *info = par->matchinfo;
    const struct iphdr *iph = ip_hdr(skb);
    bool m;

    if (info->flags & IPRANGE_SRC) {
        m  = ntohl(iph->saddr) < ntohl(info->src_min.ip);
        m |= ntohl(iph->saddr) > ntohl(info->src_max.ip);
        m ^= !!(info->flags & IPRANGE_SRC_INV);
        if (m) {
            pr_debug("src IP %pI4 NOT in range %s%pI4-%pI4\n",
                     &iph->saddr,
                     (info->flags & IPRANGE_SRC_INV) ? "(INV) " : "",
                     &info->src_min.ip,
                     &info->src_max.ip);
            return false;
        }
    }
    if (info->flags & IPRANGE_DST) {
        m  = ntohl(iph->daddr) < ntohl(info->dst_min.ip);
        m |= ntohl(iph->daddr) > ntohl(info->dst_max.ip);
        m ^= !!(info->flags & IPRANGE_DST_INV);
        if (m) {
            pr_debug("dst IP %pI4 NOT in range %s%pI4-%pI4\n",
                     &iph->daddr,
                     (info->flags & IPRANGE_DST_INV) ? "(INV) " : "",
                     &info->dst_min.ip,
                     &info->dst_max.ip);
            return false;
        }
    }
    return true;
}

static inline int
iprange_ipv6_lt(const struct in6_addr *a, const struct in6_addr *b)
{
    unsigned int i;

    for (i = 0; i < 4; ++i) {
        if (a->s6_addr32[i] != b->s6_addr32[i])
            return ntohl(a->s6_addr32[i]) < ntohl(b->s6_addr32[i]);
    }

    return 0;
}

static bool
iprange_mt6(const struct sk_buff *skb, struct xt_action_param *par)
{
    const struct xt_iprange_mtinfo *info = par->matchinfo;
    const struct ipv6hdr *iph = ipv6_hdr(skb);
    bool m;

    if (info->flags & IPRANGE_SRC) {
        m  = iprange_ipv6_lt(&iph->saddr, &info->src_min.in6);
        m |= iprange_ipv6_lt(&info->src_max.in6, &iph->saddr);
        m ^= !!(info->flags & IPRANGE_SRC_INV);
        if (m) {
            pr_debug("src IP %pI6 NOT in range %s%pI6-%pI6\n",
                 &iph->saddr,
                 (info->flags & IPRANGE_SRC_INV) ? "(INV) " : "",
                 &info->src_min.in6,
                 &info->src_max.in6);
            return false;
        }
    }
    if (info->flags & IPRANGE_DST) {
        m  = iprange_ipv6_lt(&iph->daddr, &info->dst_min.in6);
        m |= iprange_ipv6_lt(&info->dst_max.in6, &iph->daddr);
        m ^= !!(info->flags & IPRANGE_DST_INV);
        if (m) {
            pr_debug("dst IP %pI6 NOT in range %s%pI6-%pI6\n",
                 &iph->daddr,
                 (info->flags & IPRANGE_DST_INV) ? "(INV) " : "",
                 &info->dst_min.in6,
                 &info->dst_max.in6);
            return false;
        }
    }
    return true;
}

static struct xt_match iprange_mt_reg[] __read_mostly = {
    {
        .name      = "iprange",
        .revision  = 1,
        .family    = NFPROTO_IPV4,
        .match     = iprange_mt4,
        .matchsize = sizeof(struct xt_iprange_mtinfo),
        .me        = THIS_MODULE,
    },
    {
        .name      = "iprange",
        .revision  = 1,
        .family    = NFPROTO_IPV6,
        .match     = iprange_mt6,
        .matchsize = sizeof(struct xt_iprange_mtinfo),
        .me        = THIS_MODULE,
    },
};

static int __init iprange_mt_init(void)
{
    return xt_register_matches(iprange_mt_reg, ARRAY_SIZE(iprange_mt_reg));
}

static void __exit iprange_mt_exit(void)
{
    xt_unregister_matches(iprange_mt_reg, ARRAY_SIZE(iprange_mt_reg));
}

module_init(iprange_mt_init);
module_exit(iprange_mt_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jozsef Kadlecsik <[email protected]>");
MODULE_AUTHOR("Jan Engelhardt <[email protected]>");
MODULE_DESCRIPTION("Xtables: arbitrary IPv4 range matching");
MODULE_ALIAS("ipt_iprange");
MODULE_ALIAS("ip6t_iprange");